You're looking for a desktop sharing application (Some of them can be configured to share just one application, rather than your whole desktop).
–
ServyJun 26 '13 at 16:19

You could take screenshots of the application and send it to the other PC through WCF maybe? That's the easiest (at the same time ugliest) solution I can think of.
–
PoweredByOrangeJun 26 '13 at 16:26

@PoweredByOrange That's a pretty naive implementation of screen sharing, and it doesn't really scale well. You end up sending a lot of redundant data and as such generally can't get good frame rates. There are much more sophisticated algorithms that basically send incremental changes, but at the end of the day you should probably just use an existing product for this rather than rolling your own.
–
ServyJun 26 '13 at 16:28

@Servy That is why I said it's probably the ugliest solution. But if he really wants to write his own app instead of using another tool or api, that would be an starting point.
–
PoweredByOrangeJun 26 '13 at 16:30

If I understood it right I could use WCF to receive remote objects and I can build a client which parses the objects and might show their data. Does WCF provide a feature to show the GUI of my application in a browser (IE?) without writing my own client?
–
IronKalliJun 28 '13 at 7:18

No. If you want a read only experience on another system, you will have to create a read-only client.
–
Christopher StevensonJun 28 '13 at 13:26

If viewing the area of the screen the application resides in is an option, my library RemoteViewing may be sufficient for you.

The included example server (it includes both client and server VNC) is read-only.

In the example server, instead of passing a Screen as a second argument to VncScreenFramebufferSource's constructor (that will capture the entire screen), provide a callback to the screen rectangle containing the application. That should be all you need.